Plug & Perf

The Plug & Perf completion method demands a highly reliable downhole tool that can:

  • Pump down efficiently
  • Hold a frac up to 10,000 psi
  • Mill out into small pieces

All while being extremely competitive on pricing. As with any product, improvements to any of these three performance factors could result in a degradation of another; there are trade-offs. For instance, you can choose cast iron slips to increase the performance of the isolation, but the mill out won’t be as successful as with composite lower slips.

For over a decade, the industry has been on a quest to optimize these goals by using dissolvable technology in their plugs. These materials dissolve or degrade in the well environment, significantly improving the mill-out procedure. Dissolvable plugs sound great; however, there are trade-offs.

Economics Driving Design

The dissolvable materials used in these plugs, primarily magnesium-based alloys and dissolvable elastomers, are costly, which drives service companies to optimize the amount of material used. The result is smaller plugs with smaller components, including slips and elements. The slips provide the anchor, and the element supplies the seal for achieving zonal isolation during the frac. Fully optimized components limit their ability to perform well in environments that do not match the testing fixture perfectly. Smaller slips and elements perform poorly in oval or eroded casing, which leads to failure during the frac.

Dissolution Variables

The magnesium alloys in a dissolvable plug degrade through a chemical reaction with the chlorides in the well environment. Four factors affect the material’s ability to dissolve.

First, the chemical makeup of the alloy determines how aggressively the material will react with chlorides. You would choose a material with a slower dissolve rate for wells with high chloride content due to higher reactant concentration. Because of lower reactant concentrations, you’d prefer a more aggressive dissolve with more fresh water.

Second, the amount of material in the plug will affect its dissolvability. After the frac, the wells shut in until the drill out. A dissolvable plug will react with the fluid around it during this time. The dissolution will stop if the reaction uses up all the available chlorides. The more material in the plug, the more reactants are required to dissolve fully.

Third is the fluid’s ability to contact the surface area of the dissolvable plug. When setting a plug, the components are forced together, including the elements, slips, and cones, which limits the well fluids to access the material surface area.

Fourth and finally, any residual stresses in the material will slow dissolution. Again, setting and frac’ing against the plug imparts a considerable amount of force that the slips keep in the plug. These forces help to keep the plug parts from dissolving.

The nature of the plug designs on the market today include larger components with higher material content, seals, and slips that interact in a way that limits contact with the wellbore fluids, and the stresses imparted on the material all act to reduce dissolution.

A New Approach

WellBoss has taken a different approach to achieve the best of both worlds, superior isolation and quick, efficient clean-outs. The field-proven and patented Baby Boss Dissolvable Completion System addresses all the abovementioned challenges.

The Baby Boss starts with installing small profiles on the casing at the bottom of each zone. The Baby Boss plug consists of three simple and small parts: a cone, a seal ring, and a guide. The plug runs on a traditional wireline setting tool in the same manner as a typical frac plug. When the plug reaches a point just above the appropriate profile, the setting tool fires to expand the seal ring up the cone, and release the plug in the wellbore. After the seal ring expands, it is large enough to interact with the Baby Boss profile but doesn’t touch the casing. When the frac begins, a ball lands on the plug and shifts it down to interact with the profile. The engineered profile, which is only 93% of drift, acts as the plug’s anchor & seal point, eliminating the need for slips and elements.

Baby Boss Meets All The Dissolvable Challenges

Setting the plug inside a machined component eliminates the risk of elements and slips not performing in imperfect casing. The metal-to-metal seal is similar to a ball-on-seat, proven in millions of ball drop sleeve installations. After the frac, the plug can fall off the seat without any induced stresses. This small, high surface contact and no-stress plug is the optimal condition for dissolution.

Going Beyond

Baby Boss presents several technical differentiators that take it beyond the performance of current solutions. For deployment, the plug has no moving parts that could cause an issue, enabling pump down at virtually any rate without the risk of a preset.

If frac ever goes down with a dissolvable plug on the well, the operations are on a time crunch to continue the stage. Eventually, the plug will dissolve, and you will no longer have isolation for that stage. Running another plug is not possible because you wouldn’t be able to pump passed the perforations. With Baby Boss, you can pump down as far as possible, drop off the plug, and then pump it down to the seat to re-achieve isolation.

Though most companies advertise their plugs as “fully dissolvable” if the base material and element dissolve, they still have buttons and shear media that do not dissolve. In some cases, this can be up to 100 buttons per plug. The Baby Boss is 100% dissolvable magnesium alloy; it leaves nothing behind. This system leaves the cleanest possible wellbore after dissolution.

Finally, the Baby Boss profiles act as marketer joints throughout the well to provide a more accurate depth correlation for the duration of the plug and perf operation.

Let’s Get to Work.

That well won’t complete itself. Tell us more about your completions needs and well environment, and we can provide our best recommendations.

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